Sulfonyl halide

In inorganic chemistry, sulfonyl halide groups occur when a sulfonyl () functional group is singly bonded to a halogen atom. They have the general formula , where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known. The sulfonyl chlorides and fluorides are of dominant importance in this series. Sulfonyl halides have tetrahedral sulfur centres attached to two oxygen atoms, an organic radical, and a halide. In a representative example, methanesulfonyl chloride, the S=O, S−C, and S−Cl bond distances are respectively 142.4, 176.3, and 204.6 pm. Sulfonic acid chlorides, or sulfonyl chlorides, are a sulfonyl halide with the general formula . Arylsulfonyl chlorides are made industrially in a two-step, one-pot reaction from an arene (in this case, benzene) and chlorosulfuric acid: C6H6 + HOSO2Cl -> C6H5SO3H + HCl C6H5SO3H + HOSO2Cl -> C6H5SO2Cl + H2SO4 The intermediate benzenesulfonic acid can be chlorinated with thionyl chloride as well. Benzenesulfonyl chloride, the most important sulfonyl halide, can also be produced by treating sodium benzenesulfonate with phosphorus pentachlorides. Benzenediazonium chloride reacts with sulfur dioxide and hydrochloric acid to give the sulfonyl chloride: [C6H5N2]Cl + SO2 -> C6H5SO2Cl + N2 For alkylsulfonyl chlorides, one synthetic procedure is the Reed reaction: RH + SO2 + Cl2 -> RSO2Cl + HCl Sulfonyl chlorides react with water to give the corresponding sulfonic acid: RSO2Cl + H2O -> RSO3H + HCl These compounds react readily with many other nucleophiles as well, most notably alcohols and amines (see Hinsberg reaction). If the nucleophile is an alcohol, the product is a sulfonate ester; if it is an amine, the product is a sulfonamide. Using sodium sulfite as the nucleophilic reagent, p-toluenesulfonyl chloride is converted to its sulfinate salt, . Chlorosulfonated alkanes are susceptible to crosslinking via reactions with various nucleophiles.